From patchwork Tue Nov 5 10:01:29 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mauro Carvalho Chehab X-Patchwork-Id: 3141281 Return-Path: X-Original-To: patchwork-linux-media@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 6924ABEEB2 for ; Tue, 5 Nov 2013 13:05:07 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 384A520588 for ; Tue, 5 Nov 2013 13:05:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CDDC205FC for ; Tue, 5 Nov 2013 13:05:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754865Ab3KENEf (ORCPT ); Tue, 5 Nov 2013 08:04:35 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:43289 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754724Ab3KENDt (ORCPT ); Tue, 5 Nov 2013 08:03:49 -0500 Received: from [177.143.133.66] (helo=smtp.w2.samsung.com) by bombadil.infradead.org with esmtpsa (Exim 4.80.1 #2 (Red Hat Linux)) id 1VdgIO-0007gV-Dt; Tue, 05 Nov 2013 13:03:49 +0000 Received: from mchehab by smtp.w2.samsung.com with local (Exim 4.80.1) (envelope-from ) id 1VddSC-000806-CX; Tue, 05 Nov 2013 08:01:44 -0200 From: Mauro Carvalho Chehab Cc: Mauro Carvalho Chehab , Linux Media Mailing List , Mauro Carvalho Chehab Subject: [PATCH v3 16/29] [media] stv090x: Don't use dynamic static allocation Date: Tue, 5 Nov 2013 08:01:29 -0200 Message-Id: <1383645702-30636-17-git-send-email-m.chehab@samsung.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1383645702-30636-1-git-send-email-m.chehab@samsung.com> References: <1383645702-30636-1-git-send-email-m.chehab@samsung.com> To: unlisted-recipients:; (no To-header on input) Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Dynamic static allocation is evil, as Kernel stack is too low, and compilation complains about it on some archs: drivers/media/dvb-frontends/stv090x.c:750:1: warning: 'stv090x_write_regs.constprop.6' uses dynamic stack allocation [enabled by default] Instead, let's enforce a limit for the buffer. Considering that I2C transfers are generally limited, and that devices used on USB has a max data length of 64 bytes for the control URBs. So, it seem safe to use 64 bytes as the hard limit for all those devices. On most cases, the limit is a way lower than that, but this limit is small enough to not affect the Kernel stack, and it is a no brain limit, as using smaller ones would require to either carefully each driver or to take a look on each datasheet. Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-frontends/stv090x.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/media/dvb-frontends/stv090x.c b/drivers/media/dvb-frontends/stv090x.c index 56d470ad5a82..23e872f84742 100644 --- a/drivers/media/dvb-frontends/stv090x.c +++ b/drivers/media/dvb-frontends/stv090x.c @@ -35,6 +35,9 @@ #include "stv090x.h" #include "stv090x_priv.h" +/* Max transfer size done by I2C transfer functions */ +#define MAX_XFER_SIZE 64 + static unsigned int verbose; module_param(verbose, int, 0644); @@ -722,9 +725,16 @@ static int stv090x_write_regs(struct stv090x_state *state, unsigned int reg, u8 { const struct stv090x_config *config = state->config; int ret; - u8 buf[2 + count]; + u8 buf[MAX_XFER_SIZE]; struct i2c_msg i2c_msg = { .addr = config->address, .flags = 0, .buf = buf, .len = 2 + count }; + if (2 + count > sizeof(buf)) { + printk(KERN_WARNING + "%s: i2c wr reg=%04x: len=%d is too big!\n", + KBUILD_MODNAME, reg, count); + return -EINVAL; + } + buf[0] = reg >> 8; buf[1] = reg & 0xff; memcpy(&buf[2], data, count);